Selectively Applied Gradient Coating Compositions

ABSTRACT

Surface modifications and coating materials are provided that may be applied to a substrate to reduce or eliminate damage that would accrue to do environmental effects or operational stress when incorporated into a device such as a heat exchanger. Structured ceramic surface modification materials may be incorporated into the surface modification and may optionally include a gradient in one or more physical or chemical property.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to PCT Application No.PCT/US2019/065978, filed on Dec. 12, 2019, and claims the benefit ofU.S. Provisional Application Nos. 62/989,092, filed on Mar. 13, 2020,62/989,150, filed on Mar. 13, 2020, 63/038,642, filed on Jun. 12, 2020,63/038,693, filed on Jun. 12, 2020, and 63/039,965, filed on Jun. 16,2020, all of which are incorporated herein by reference in theirentireties.

FIELD OF THE INVENTION

The invention relates to coating materials, in particular coatingmaterials that provide a gradient of one or more physical or chemicalproperty, that mitigate environmental or operational damage, such ascorrosion, to a substrate on which the coating material is applied.

BACKGROUND

Heat exchangers and other systems of interest, when exposed to the localenvironment, are subjected to conditions which can affect theirperformance and ultimately their usefulness. The impacts that can beobserved are localized corrosion, water and frost accumulation thatincrease corrosion, debris accumulation or abrasion by airborne debris,which can reduce the effectiveness of corrosion protections or lead tomicrobial growth and subsequent corrosion. To further the example,significantly more debris accumulation occurs on the leading edgesurfaces of a heat exchanger than on the trailing edge. Wateraccumulation during condensation can aggregate on the trailing edge ofthe heat exchanger surface, increasing corrosion damage. Roadway wearoccurs in the regions of tire contact and oil accumulation occurs in thecenter of the lanes, both of which alter the wear and corrosion patternsof the roadway. In order to increase the performance of these devicesand systems, it is desirable to directly address these conditions in atargeted manner, at the region of interest.

BRIEF SUMMARY OF THE INVENTION

Coating compositions and methods of use thereof are provided herein.

In one aspect, a composition in the form of a coating or modification ona surface of a substrate is provided, wherein the coating ormodification includes a gradient in at least one physical or chemicalproperty across at least a portion of the substrate surface. Forexample, the at least one physical or chemical property of the gradientmay include, but is not limited to, one or more of thickness, density,pore size, pore size distribution, pore filling fraction, chemical orphysical composition, oxidation state, metal concentration, crosslinkingdensity, isoelectric point, electrical conductivity, thermalconductivity, and capacitance. In some embodiments a gradient, forexample, a gradient of any of the above properties can vary by about 1%to about 99%, about 5% to about 95%, about 10% to about 90%, about 20%to about 80%, or any of about 1%, about 5%, about 10%, about 20%, about30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%,about 95%, or about 99%, or any of at least about 1%, about 5%, about10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%,about 80%, about 90%, about 95%, or about 99%, relative to the largestvalue of a given property of the coating or modification or the largestvalue of a given property on the substrate.

In some embodiments, the coating or modification that includes thegradient in at least one physical or chemical property is in a singlelayer on the substrate surface. For example, the coating or modificationmay include a ceramic, a polymeric material, or a self-assembledmonolayer.

In some embodiments, the coating or modification includes a plurality oflayers, wherein at least one of the layers includes the gradient in atleast one physical or chemical property. For example, the at least onelayer that includes the gradient may include a ceramic, a polymericmaterial, or a self-assembled monolayer. In one embodiment, theplurality of layers includes a first layer that includes the gradient inat least one physical or chemical property in contact with thesubstrate, and a second functional material layer that does not includethe gradient over the first layer

In another embodiment, the plurality of layers includes a first layerthat does not include the gradient in contact with the substrate and asecond functional material layer that includes the gradient over thefirst layer.

In some embodiments, the coating or modification is applied in aspatially discrete area of the substrate surface, and one or more areaof the substrate surface does not include the coating or modification.For example, the coating or modification may be applied in a pluralityof spatially discrete areas of the surface of the substrate. In someembodiments, about 1% to about 99%, about 5% to about 95%, about 10% toabout 90%, about 20% to about 80%, or any of about 1%, about 5%, about10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%,about 80%, about 90%, about 95%, or about 99%, or any of at least about1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%,about 60%, about 70%, about 80%, about 90%, about 95%, or about 99% ofthe substrate surface is covered with the coating, layer(s), ormodification.

In some embodiments, the coating or modification is spatially continuousacross the entire area or substantially the entire area of the substratesurface.

In some embodiments, the substrate is modified with a conversion coatingor primer on the entire substrate surface or substantially the entiresubstrate surface, and a layer that includes the gradient in at leastone physical or chemical property is coated on top of the conversioncoating or primer. In one embodiment, the layer that includes thegradient in at least one physical or chemical property is applied in aspatially discrete area of the conversion coating or primer, and one ormore area of the conversion coating or primer does not include the layerthat includes the gradient. In one embodiment, the layer that includesthe gradient in at least one physical or chemical property is applied ina plurality of spatially discrete areas of the conversion coating orprimer. In one embodiment, the layer that includes the gradient in atleast one physical or chemical property is spatially continuous acrossthe entire area or substantially the entire area of the conversioncoating or primer. In some embodiments, the conversion coating or primerincludes one or more of a chromate, a fluorozirconate, a fluorotitanate,a sol gel, a phosphate, zirconium, a rare earth metal, and a blue orblack oxide. In some embodiments, the layer that includes the gradientin at least one physical or chemical property includes a ceramic, apolymeric material, or a self-assembled monolayer.

In some embodiments, a layer that includes the gradient in at least onephysical or chemical property is coated on at least a portion of thesubstrate surface and a uniform or substantially uniform functionalmaterial layer is coated on top of the layer that includes the gradientand across the entire area or substantially the entire area of thesubstrate surface. In some embodiments, the layer that includes thegradient in at least one physical or chemical property includes aceramic, a polymeric material, or a self-assembled monolayer.

In some embodiments, the coating or modification or layer that includesthe gradient in at least one physical or chemical property comprises orconsists of a ceramic material. For example, the ceramic material may bea binderless ceramic material with a crystallinity greater than about20%. The ceramic material may include a metal oxide, a hydrate of ametal oxide, a metal hydroxide, and/or a hydrate of a metal hydroxide.In some embodiments, the ceramic material includes a metal hydroxide,wherein at least a portion of the metal hydroxide is in the form oflayered double hydroxide. In some embodiments, the ceramic materialincludes one or more property selected from: a surface area of about 10m² to 1500 m² per square meter of projected substrate area; a surfacearea of about 15 m² to 1500 m² per gram of ceramic material; a mean porediameter of about 2 nm to about 20 nm; a thickness of about 0.2micrometers to about 25 micrometers; a porosity greater than about 10%;and a void volume of about 100 mm³/g to about 7500 mm³/g as determinedby mercury intrusion porosimetry.

In some embodiments, the coating or modification or layer that includesthe gradient in at least one physical or chemical property comprises orconsists of a latex, a paraffin (an alkane), an alkene, an alcohol, anacrylic, an alkyd, an enamel, an epoxy, a siloxane, a fluoropolymer, ora urethane.

In some embodiments, the coating or modification or layer that includesthe gradient in at least one physical or chemical property includes amolecule with a head group and a tail group, for example, wherein thehead group includes a silane group, a sulfonate group, a sulfonic acidgroup, a boronate group, a boronic acid group, a phosphonate group, aphosphonic acid group, a carboxylate group, a carboxylic acid group, avinyl group, a hydroxide group, an alcohol group, a thiolate group, athiol group, and/or an quaternary ammonium group, and wherein the tailgroup includes a hydrocarbon group, a fluorocarbon group, a vinyl group,a phenyl group, an epoxide group, an acrylic group, an acrylate group, ahydroxyl group, a carboxylic acid group, a thiol group, and/or aquaternary ammonium group.

In some embodiments, the substrate surface is a surface of a heatexchanger, a vehicle, an aircraft, a watercraft, or a bridge, or anyother surface that is susceptible to environmental wear or degradationunder conditions in the environment where it is situated or operated.For example, the substrate surface may be a surface of a brazed aluminumheat exchanger, a copper tube-aluminum fin heat exchanger, or a steeltube-aluminum fin heat exchanger.

In another aspect, a heat exchange or a component thereof is provided,wherein a composition as described herein (i.e., a coating ormodification that includes a gradient in at least one physical orchemical property across at least a portion of the substrate surface, asdescribed herein) is applied to a surface of the heat exchanger or thesurface of a component of the heat exchanger. For example, the heatexchanger may be a brazed aluminum heat exchanger, a coppertube-aluminum fin heat exchanger, or a steel tube-aluminum fin heatexchanger. The heat exchanger surface or component may exhibit greaterresistance to environmental damage than an identical heat exchanger orcomponent that does not include the composition described herein.

In another aspect, a method is provided for protecting a substrate fromenvironmental damage. The method includes applying a composition asdescribed herein (i.e., a coating or modification that includes agradient in at least one physical or chemical property across at least aportion of the substrate surface) to a substrate, wherein the substrateexhibits greater resistance to environmental damage than an identicalsubstrate that does not include the composition. For example, theenvironmental damage may include, but is not limited to, one or more ofcorrosion, debris accumulation, water or ice accumulation, biofouling,and abrasion. In one embodiment, corrosion due to water or iceaccumulation is reduced or prevented, in comparison to an identicalsubstrate that does not include the composition as described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows drying rates of ceramic coated panels as described inExample 43.

DETAILED DESCRIPTION

Selective application of coating compositions can be used to provideprotection against environmental damage. Furthermore, over time, theconditions to be prevented or treated change. This can be addressedthrough a layered coating structure which provides different protectionsas the layers are altered, for example, through the lifetime of adevice.

Provided herein are coating compositions and substrate modifications tominimize environmental wear or degradation, such as corrosion, in areaswhere environmental exposure and damage is especially challenging, suchas on edges, material or composite interfaces, regions of low velocity,regions of high electrochemical corrosion potential, or regions that areexposed to or susceptible to excess moisture, salt, debris accumulation,biofouling, or abrasion.

Coating materials or surface modification may be used to apply morecorrosion resistant materials or to promote or enhance movement of aliquid, such as water, away from a substrate, in areas of highenvironmental exposure or stress, or stress due to operational factorsduring usage of a device, to partially coat a component in instanceswhere coating of an entire surface or device is not needed, to protectmaterials differently over time, e.g., through differences in thicknessof coating material or surface modification across a substrate surfaceor through a surface normal gradient (for example, a gradient of one ormore chemical or physical property from the top of the coating materialor surface modification to the bottom which is in contact with thesubstrate surface) and/or as a branding or cost cutting measure.

Selective application of coating materials or surface modifications canalso be used to achieve complementary benefit such as corrosionresistance, while minimizing potential negative impacts such as heattransfer losses due to thermal resistance of the coating.

One application of use involves heat exchangers. Some outdoor heatexchangers corrode and fail at very specific locations due to standingwater after a rain, sprinklers, proximity to or use in marineenvironments, or animal, e.g., cat, urination. Other environmentalstresses that may be mitigated or eliminated by application of thecompositions and surface modifications described herein include exhaustpollution, urban pollution, dust/debris, fertilizer, road salt, sand,marine aerosols, industrial emissions (e.g., refinery, water treatment,manufacturing), or microbial (e.g., bacterial, fungal) or viral exposureand/or degradation, including biofilm formation (i.e., anti-microbial,anti-bacterial, anti-fungal, or anti-viral coating or surfacemodification). Spatial gradients of properties can be used to create agradient effect. For example, a spatial gradient of porosity thatdirectionally wicks a fluid such as water and “pumps” it from onedirection to another may be used for anti-corrosion and other purposes,such as enhanced drying or fluid transfer.

In some embodiments, the coating or surface modification may render aheat exchanger or component thereof resistant to impinging pollutants(e.g., slaughterhouse particles, corrosive aerosols, etc.) and increasethermal resistance to decrease frosting rate, by reducing thermalconductivity and thereby increasing surface temperature. Downstream inthe fin pack, the coating may be different to reduce corrosionresistance rate and improve heat transfer/frost suppression properties.

A coating or surface modification may be applied to an entire substratesurface or selectively (to one or more portion of a substrate surface,such as to one or more area that is exposed to adverse environmentalconditions or subject to environmental or operational stress). Incertain embodiments described herein, coating or surface modificationsare configured as a gradient (i.e., spatial variability) in one or moredimension, across a substrate surface or across a device or a portion orcomponent of a device. Exemplar material parameters may includegradients in material density, pore size distribution, pore filling(i.e., filling fraction, or spatial gradient of materials filling poresof a porous material), or material thickness.

Methods of mitigating or preventing environmental or operational damageto a substrate or a device or component into which the substrate isincorporated are provided. The methods include spatially continuous ordiscrete application of any of the coating or surface modificationmaterials described herein to a substrate, including one or morematerial that includes a gradient in at least one chemical or physicalproperty, wherein the substrate is resistant to environmental oroperational damage, such as, but not limited to, corrosion, debrisaccumulation, water or ice accumulation, biofouling, or abrasion, incomparison to a substrate that does not include the coating or substratemodification.

Definitions

Numeric ranges provided herein are inclusive of the numbers defining therange.

“A,” “an” and “the” include plural references unless the context clearlydictates otherwise.

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Other elements may optionallybe present other than the elements specifically identified by the“and/or” clause, whether related or unrelated to those elementsspecifically identified unless clearly indicated to the contrary. Thus,as a non-limiting example, a reference to “A and/or B,” when used inconjunction with open-ended language such as “comprising” can refer, inone embodiment, to A without B (optionally including elements other thanB); in another embodiment, to B without A (optionally including elementsother than A); in yet another embodiment, to both A and B (optionallyincluding other elements); etc.”

“Binder” or binding agent is any material or substance that holds ordraws other materials together to form a cohesive whole mechanically,chemically, by adhesion or cohesion.

“Binderless” refers to absence of a binder that may be exogenously addedto a primary material to improve structural integrity, particularly withregard to an organic binder or resin (e.g., polymers, glues, adhesives,asphalt) or inorganic binder (e.g., lime, cement glass, gypsum, etc.).

“Capillary climb” refers to a surface tension driven flow of liquid up asample (the capillary climb is parallel to, and opposite to, thedirection of the force (vector) due to gravity) upon contact with a freesurface of liquid as a result of the porous substrate.

A “ceramic” or “ceramic material” refers to a solid material includingan inorganic compound of a metal or a metalloid, and a non-metal, withionic or covalent bonds. A “non-metal” may include oxygen (oxideceramic), or carbon (carbide) or nitrogen (nitride) (non-oxideceramics). A “metal” may include a non-hydrogen element of Group 1 ofthe periodic table, an element of Groups 2-12 of the periodic table, oran element from the p-block (Groups 12-17 of the periodic table), e.g.,Al, Ga, In, Tl, Sn, Pb, Bi, or combinations thereof. A “metalloid” mayinclude B, Si, Ge, As, Sb, Se, Te, or Po, or combinations thereof.

“Contact angle” refers to the angle measured through a liquid between asurface and the liquid-vapor interface at the contacting surface.

“Contiguous” or “contiguity” refers to pores and structures that containwalls and features in direct contact with one another or that share acommon wall across a region or dimension large relative to an individualpore or structure.

A “conversion coating” refers to a surface layer in which reactants arechemically reacted with the surface to be treated, which converts thesubstrate into a different compound. This process is typically notadditive or a deposition, but may result in a small mass change.

“First quartile pore diameter” refers to the value of the pore diameterat which the cumulative pore surface area determined in the direction ofincreasing pore size is equivalent to 25% of the total cumulative poresurface area as determined by BJH gas adsorption/desorptionmeasurements.

A “functional material layer” refers to a layer of material which mayserve as the uppermost surface layer interacting with the surroundingenvironment or may serve as an interfacial layer for subsequentmaterials (intermediate layer between two other layers of material). Afunctional material layer imparts one or more desirable functionalproperties to the underlying substrate and/or the material on which itis deposited.

A “gradient” refers herein to a quantitative increase or decrease in oneor more physical or chemical property of a material observed by passingspatially from one point to another point along a substrate surface onwhich the material is situated or immobilized, and varying in an x, y,or z direction in Cartesian coordinates on or through the material.Nonlimiting examples of gradient properties include thickness, density,hardness, ductility, pore size, pore size distribution, pore fillingfraction, or chemical or physical composition, including but not limitedto, oxidation state, metal concentration, or crosslinking density, forexample, resulting in variation in isoelectric point, electricalconductivity, thermal conductivity, capacitance, etc.

“Hydrophilic” refers to a surface that has a high affinity for water.Contact angles can be very low (e.g. less than 30 degrees as measuredfrom the surface through the liquid water in the presence of air) and/orimmeasurable.

“Layered double hydroxide” refers a class of ionic solids characterizedby a layered structure with the generic sequence [AcB Z AcB]_(n), wherec represents layers of metal cations, A and B are layers of hydroxideanions, and Z are layers of other anions and/or neutral molecules (suchas water). Layered double hydroxides are also described in PCTApplication No. PCT/US2017/052120, which is incorporated by referenceherein in its entirety.

A “macro void” refers to a geometric space within solid that has acharacteristic dimension substantially larger than the characteristicdimension of an individual pore or feature (e.g., thickness), forexample, at least about 5× to about 10× or about 10× to about 100×greater than the characteristic dimension.

“Mean” refers to the arithmetic mean or average.

“Mean pore diameter” is calculated using total surface area and totalvolume measurements from the Barrett-Joyner-Halenda (BJH)adsorption/desorption method as 4 times the total pore volume divided bythe total surface area (4V/A), assuming a cylindrical pore.

“Multimodal” refers to a distribution which contains more than onedifferent mode that appears as more than one distinct peak.

“Permeability” in fluid mechanics is a measure of the ability of aporous material to allow fluids to pass through it. The permeability ofa medium is related to the porosity, but also to the shapes of the poresin the medium and their level of connectedness.

“Pore size distribution” refers to the relative abundance of each porediameter or range or pore diameters as determined by mercury intrusionporosimetry (MIP) and Washburn's equation.

“Porosity” is a measure of the void (i.e., “empty”) spaces in amaterial, and is a fraction of the volume of voids, i.e., macro voids.over the total volume, between 0 and 1, or as a percentage between 0%and 100%. Porosities disclosed herein were measured by mercury intrusionporosimetry.

“Porous” refers to spaces, holes, or voids within a solid material.

“Superhydrophobic” refers to a surface that is extremely difficult towet. The contact angle of a water droplet on a superhydrophobic materialhere a superhydrophobic surface refers to a sessile drop contactangles >150°. Highly hydrophobic contact angles are >120°. Contactangles noted here are angles formed between the surface through theliquid.

“Surface area per square meter of projected substrate area” refers tothe actual measured surface area, usually measured in square meters,divided to the surface area of the substrate if it were atomicallysmooth (no surface roughness), also typically in square meters.

“Synergy” or “synergistic” refers to the interaction or cooperationbetween two or more substances, materials, or agents to produce acombined effect that is greater (positive synergy) or lesser (negativesynergy) than the sum of their separate, individual effects.

“Thickness” refers to the length between the surface of the substrateand the top of the surface modification (e.g., ceramic) material.

“Third quartile pore diameter” refers to the value of the pore diameterat which the cumulative pore surface area determined in the direction ofincreasing pore size is equivalent to 75% of the total cumulative poresurface area as determined by BJH gas adsorption/desorptionmeasurements.

“Tortuosity” refers to the fraction of the shortest pathway through aporous structure Δl and the Euclidean distance between the starting andend point of that pathway Δx.

“Tunable” refers to the ability of a function, characteristic, orquality of a material to be changed or modified.

Selective Coating and Surface Modification Materials

The selective coating of a substrate, such as a surface of a heatexchanger, can be performed in multiple ways, such as: partial(selective) coating on a portion of the surface of a substrate, wheresome locations are uncoated and some are coated, based on localcorrosion resistance need or other needs, such as, but not limited to,limiting microbial growth in regions of high moisture (e.g., Legionella)or movement of a liquid, such as water, away from the substrate;complete coating of a substrate with first material A and partialcoating of a second material B over the first material (i.e., selectivecoating of second material B over a portion (one or more areas) of thesurface of first material A), where the second material may be the sameas or different from the first material; and a gradient within a coatingacross the substrate based on need for protection from environmental oroperational stress conditions.

Gradients herein are spatially variable with respect to at least onechemical or physical property. For example, a coating or surfacemodification material A may be a uniform material on a substrate surfaceor may include a spatial gradient (variability) in one or more propertysuch as, but not limited to, material density, pore size distribution,pore filling fraction, or thickness. Additionally, an optional secondmaterial B may also be applied over material A, which may be a uniformmaterial or may possess spatial variability in one or more property,such as, but not limited to, material density, pore size distribution,thickness, and/or filling fraction of the pores of material A. In someembodiments, an optional third material C may also be selectivelyapplied and may be a uniform material across the substrate or across thematerial directly below or may possess spatial variability in one ormore property, such as, but not limited to, material density, pore sizedistribution, thickness, and/or filling fraction of the pores ofmaterial B. In some embodiments, material C is applied over a stack ofmaterials, such as, but not limited to, A-B-A, and may possess spatialvariability in one or more property, such as, but not limited to,material density, pore size distribution, thickness, and/or fillingfraction of the pores of the material directly below material C, e.g.,material A. Additional optional layers of uniform or gradient materialsmay also be included. The coating or surface modification material(s)may be applied continuously across the substrate surface or in one ormore discrete (selective) areas, such as areas of the substrate that aresubject to environmental or operational stress in an application of usefor a device or component into which the substrate is incorporated.

A gradient layer as disclosed herein may include a gradient of one ormore property of a structural layer. For example, a gradient may includehigher porosity near a joint, a change in structural composite thicknesson a panel, e.g., thicker near the bottom or edges from the draining anddryout of an immersion process at a specific temperature, selectivelyspraying materials in select regions, adding additional coats ofmaterials in select regions, configuration of spray applicationresulting in a greater addition of material at the leading edge, or acomposition change impacting electrochemical potential.

A gradient may be developed during processing of a structural layer, forexample, by changing concentration levels of reactants or components ofthe composition (dropping) during processing, which results in changesin the composition through the thickness of the coating, and/or changingtemperature, e.g., temperature of the processing bath, during processingto change structure or to change part temperature during processing, orhaving variable temperature zones during processing, such as a hot zoneand a cold zone of the part to result in thicker, thinner, or differentmaterials, e.g., structured ceramic materials. Modification of the localchemical reactivity through mechanical part agitation, fluid advection,addition of localized heat or light, pressure differences and/orgravitational settling differences can also be used to generate gradientproperties. The drying and curing process can also be used to generateproperty gradients through the use of select temperature zones, dryingorientations, and/or selective light addition.

In some embodiments, one or more coating or surface modificationmaterial (e.g., materials A-C) is a structured ceramic, such as abinderless ceramic surface modification material, for example, withpores that may be filled, unfilled, or partially filled, optionally in amanner that produces a gradient with respect to partial filling of thepores with a second material. In one embodiment, the ceramic materialincludes a contiguous network of pores filled with a second material,such as a polymer material.

In some embodiments, a surface modification material may be a conversioncoating or primer (for example, but not limited to, trivalent chromiumphosphate, other chromates, fluorozirconates, fluorotitanates, sol gels,phosphates, blueing or black oxide coatings or anodizing).

In some embodiments, one or more surface modification material isapplied to a paint primer. For example, a deposited material may be apaint, such as a latex, acrylic, alkane, alkene, alcohol, enamel, epoxy,siloxane, polysilazane, fluoropolymer, or urethane. For example, adeposited material may be a natural or processed fatty acid, alcohol,hydrocarbon, or oil, such as linoleic, palmitic, oleic acid, glycerol,paraffin, turpentine, tall oil, linseed oil, palm oil, tung oil orboiled linseed oil, hydrogenated fatty acids, refined glycerol,distilled paraffin, mineral oil, or refined palm oil.

In some embodiments, one or more surface modification material is amonolayer chemistry, which may provide any of an array of properties,such as, but not limited to, wettability, sealant, optical, etc.

Many substrates have multimetal components, such as copper-aluminum heatexchangers, steel-aluminum heat exchangers, brazed aluminum heatexchangers, screws and rivets in bridges and vehicles, and othercomponents that contain composite interfaces. Selective protection inthese composite scenarios can provide additional protection for galvaniccorrosion susceptible metal couples (e.g. selective anode protection)for a wide variety of environments and anodic/cathodic areas. Othersubstrates, homogenous or heterogenous in composition, contain localareas susceptible to corrosion due to local environments such as localabrasion, standing liquids, or air flow gradients.

In some embodiments, the substrate is a heat exchanger or componentthereof, such as a microchannel heat exchanger. Other embodimentsinclude bridges, aircraft, vehicles, and watercraft, or componentsthereof.

Nonlimiting examples of properties and compositions of a coating orsurface modification include a layer (“n”), as described herein:

n₁ Conversion coating or primer—continuous coverage without gradient

n₂ Conversion coating or primer—continuous coverage with gradient

n₃ Conversion coating or primer—selective (discrete) coverage withoutgradient

n₄ Conversion coating or primer—selective coverage with gradient

n₅ Structured ceramic—continuous coverage without gradient

n₆ Structured ceramic—continuous coverage with gradient

n₇ Structured ceramic—selective coverage without gradient

n₈ Structured ceramic—selective coverage with gradient

n₉ Deposited monolayer/paint/oil/resin—continuous coverage withoutgradient

n₁₀ Deposited monolayer/paint/oil/resin—continuous coverage withgradient

n₁₁ Deposited monolayer/paint/oil/resin—selective coverage withoutgradient

n₁₂ Deposited monolayer/paint/oil/resin—selective coverage with gradient

Nonlimiting permutations of coatings or surface modifications (n=“A”,“B”, “C”, . . . , where A, B, C, etc. are listed in order of applicationor proximity to the substrate, for example, wherein A is a material incontact with or proximal to the substrate or the bottommost material ina plurality of layers of material), include:

A₁-B₁₁ (continuous coverage conversion coating+selective coverage paint)

A₁-B₁₀ (continuous coverage conversion coating+continuous coveragegradient paint)

A₁-B₁₂ (continuous coverage conversion coating+selective coveragegradient paint)

A₁-B₆ (continuous coverage primer+continuous coverage gradientstructured ceramic)

A₁-B₇ (continuous coverage primer+selective coverage structured ceramic)

A₁-B₈ (continuous coverage primer+selective coverage gradient structuredceramic)

A₁-B₅-C₉-D₁₁ (continuous coverage conversion coating+continuous coveragestructured ceramic+continuous coverage functional materiallayer+selective coverage paint)

A₁-B₅-C₁₀ (continuous coverage conversion coating+continuous coveragestructured ceramic+continuous coverage gradient functional materiallayer)

A₁-B₅-C₁₁ (continuous coverage conversion coating+continuous coveragestructured ceramic+selective functional material layer)

A₁-B₅-C₁₂ (continuous coverage conversion coating+continuous coveragestructured ceramic+selective coverage gradient functional materiallayer)

A₃ (selective coverage conversion coatings)

A₅-B₉-C₁₁ (continuous coverage structured ceramic+continuous coveragefunctional material layer+coverage selective paint)

A₅-B₁₀ (continuous coverage structured ceramic+continuous coveragegradient functional material layer)

A₅-B₁₁ (continuous coverage structured ceramic+selective coveragefunctional material layer)

A₅-B₁₂ (continuous coverage structured ceramic+selective coveragegradient functional material layer)

A₆ (continuous coverage gradient structured ceramic)

A₆-B₉ (continuous coverage gradient structured ceramic+continuouscoverage functional material layer)

A₆-B₁₀ (continuous coverage gradient structured ceramic+continuouscoverage gradient functional material layer)

A₆-B₁₁ (continuous coverage gradient structured ceramic+selectivecoverage functional material layer)

A₆-B₁₂ (continuous coverage gradient structured ceramic+selectivecoverage gradient functional material layer)

A₇ (selective coverage structured ceramic)

A₇-B₉ (selective coverage structured ceramic+continuous coveragefunctional material layer)

A₇-B₁₁ (selective coverage structured ceramic+selective coveragefunctional material layer)

A₈ (selective coverage gradient structured ceramic)

A₉-B₁₁ (continuous coverage monolayer coating+selective coverage paint)

A₁₀ (continuous coverage gradient paint)

A₁₁ (selective coverage paint)

A₁₂ (selective coverage gradient paint)

Structured Ceramic Materials

A continuous or discrete coating or surface modification material asdescribed herein may be a structured ceramic, for example, a binderless(e.g., surface immobilized) ceramic, such as a binderless ceramic with acrystallinity greater than about 20%. In some embodiments, thestructured ceramic is porous. Nonlimiting examples of ceramic materialsare provided in PCT/US19/65978, which is incorporated herein byreference in its entirety.

The ceramic material may include a metal oxide and/or hydroxide ceramic,for example, a single metal or mixed metal oxide and/or hydroxideceramic. In some embodiments, the ceramic material includes a metalhydroxide and/or hydroxide ceramic, for example, a single metal or mixedmetal oxide and/or hydroxide ceramic. In some embodiments, the ceramicmaterial includes a metal oxide and a metal hydroxide ceramic, whereinthe metal oxide and the metal hydroxide include the same or differentsingle metal or mixed metal. In some embodiments, the ceramic materialincludes a metal oxide and/or a metal hydroxide ceramic, wherein thesubstrate is hydrated by water or other compounds resulting in a changeof surface energy and potentially the ratio of metal oxide to metalhydroxide composition of the ceramic. In some embodiments, the ceramicmaterial includes a metal hydroxide, wherein at least a portion of themetal hydroxide is in the form of a layered double hydroxide, e.g., atleast about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%,65%, 70%, 75%, 80%, 85%, 90%, or 95% of the metal hydroxide is layereddouble hydroxide.

In some embodiments, a “metal oxide” or “metal hydroxide” may be in theform of a hydrate of a metal oxide or metal hydroxide, respectively, ora portion of the metal oxide or metal hydroxide may be in the form of ahydrate of a metal oxide or metal hydroxide, respectively.

A mixed metal oxide or mixed metal hydroxide may include, for example,oxides or hydroxides, respectively, of more than one metal, such as, butnot limited to, iron, cobalt, nickel, copper, manganese, chromium,titanium, vanadium, zirconium, molybdenum, tantalum, zinc, lead, tin,tungsten, cerium, praseodymium, samarium, gadolinium, lanthanum,magnesium, aluminum, or calcium.

In some embodiments, the ceramic material is a binderless ceramicmaterial, i.e., deposited onto a substrate without a binder. In someembodiments, the ceramic materials immobilized on the substrate.

In some embodiments, the ceramic material has an open cell porousstructure, for example, characterized by one or more of: ability toeffect capillary rise of a liquid having a low surface tension (e.g.,less than about 25 mN/m, such as isopropanol) at greater than about 5 mmup a surface against gravity in a closed container in 1 hour; surfacearea of about 0.1 m²/g to about 10,000 m²/g; mean pore size of about 10nm to about 1000 nm or about 1 nm to about 1000 nm; pore volume asmeasured by mercury (Hg) intrusion porosimetry of about 0 to about 1cc/g; and tortuosity of about 1 to about 1000 as defined by the lengthof a fluid path to the shortest distance, the “arc-chord ratio”; and/orpermeability of about 1 to about 10,000 millidarcy.

In some embodiments, the ceramic material is porous, with a porosity ofabout 5% to about 95%. In some embodiments, the porosity may be any ofat least about or greater than about 5%, 10%, 15%, 20%, 25%, 30%, 35%,40%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In someembodiments, the porosity is about 10% to about 90%, about 30% to about90%, about 40% to about 80%, or about 50% to about 70%.

In some embodiments, the porous ceramic material has a permeability ofabout 1 to 10,000 millidarcy. In some embodiments, the permeability maybe any of at least about 1, 10, 100, 500, 1000, 5000, or 10,000millidarcy. In some embodiments, the permeability is about 1 to about100, about 50 to about 250, about 100 to about 500, about 250 to about750, about 500 to about 1000, about 750 to about 2000, about 1000 toabout 2500, about 2000 to about 5000, about 3000 to about 7500, about5000 to about 10,000, about 1 to about 1000, about 1000 to about 5000,or about 5000 to about 10,000 millidarcy.

In some embodiments, the porous ceramic material includes a void volumeof about 100 mm³/g to about 7500 mm³/g, as determined by mercuryintrusion porosimetry. In some embodiments, the void volume is any of atleast about 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1500,2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, or7500 mm³/g. In some embodiments, the void volume is any of about 100 toabout 500, about 200 to about 1000, about 400 to about 800, about 500 toabout 1000, about 800 to about 1500, about 1000 to about 2000, about1500 to about 3000, about 2000 to about 5000, about 3000 to about 7500,about 250 to about 5000, about 350 to about 4000, about 400 to about3000, about 250 to about 1000, about 250 to about 2500, about 2500 toabout 5000, or about 500 to about 4000 mm³/g.

A porous ceramic material as disclosed herein may be characterized byits interaction with liquid materials. As previously noted, the ceramicmaterial may be characterized the ability to effect capillary rise of aliquid having a low surface tension (e.g., less than about 25 mN/m, suchas isopropanol) at greater than about 5 mm up a surface against gravityin a closed container in 1 hour. Other solvents with surface tensionless than about 25 mN/m at 20° C. of may be used including, but notlimited to, Perfluorohexane, Perfluoroheptane, Perfluorooctane, n-Hexane(HEX), Polydimethyl siloxane (Baysilone M5), tert-Butylchloride,n-Heptane, n-Octane (OCT), Isobutylchloride, Ethanol, Methanol,Isopropanol, 1-Chlorobutane, Isoamylchloride, Propanol, n-Decane (DEC),Ethylbromide, Methyl ethyl ketone (MEK), n-Undecane, Cyclohexane. Othersolvents with surface tension at 20° C. of >25 mN/m may be usedincluding: Acetone (2-Propanone), n-Dodecane (DDEC), Isovaleronitrile,Tetrahydrofuran (THF), Dichloromethane, n-Tetradecane (TDEC),sym-Tetrachloromethane, n-Hexadecane (HDEC), Chloroform, 1-Octanol,Butyronitrile, p-Cymene, Isopropylbenzene, Toluene, Dipropylene glycolmonomethylether, 1-Decanol, Ethylene glycol monoethyl ether (EthylCellosolve), 1,3,5-Trimethylbenzene (Mesitylene), Benzene, m-Xylene,n-Propylbenzene, Ethylbenzene, n-Butylbenzene, 1-nitro propane,o-Xylene, Dodecyl benzene, Fumaric acid diethylester, Decalin,Nitroethane, Carbon disulfide, Cyclopentanol, 1,4-Dioxane, 1,2-Dichloroethane, Chloro benzene, Dipropylene glycol, Cyclohexanol,Hexachlorobutadiene, Bromobenzene, Pyrrol (PY), N,N-dimethyl acetamide(DMA), Nitromethane, Phthalic acid diethylester, N,N-dimethyl formamide(DMF), Pyridine, Methyl naphthalene, Benzylalcohol, Anthranilic acidethylester, Iodobenzene, N-methyl-2-pyrrolidone, Tricresylphosphate(TCP), m-Nitrotoluene, Bromoform, o-Nitrotoluene, Phenylisothiocyanate,a-Chloronaphthalene, Furfural (2-Furaldehyde), Quinoline,1,5-Pentanediol, Aniline(AN), Polyethylene glycol 200 (PEG), Anthranilicacid methylester, Nitrobenzene, a-Bromonaphthalene (BN), Diethyleneglycol (DEG), 1,2,3-Tribromo propane, Benzylbenzoate (BNBZ),1,3-Diiodopropane, 3-Pyridylcarbinol (PYC), Ethylene glycol (EG),2-Aminoethanol, sym-Tetrabromoethane, Diiodomethane (DI), Thiodiglycol(2,2′-Thiobisethanol) (TDG), Formamide (FA), Glycerol (GLY), Water (WA),and Mercury

The porous ceramic surface modification material may possess the abilityto effect capillary rise of water, at various temperatures. Thesematerials may have the ability to separate miscible materials and binaryazeotropes, such as ethanol-water, ethyl acetate-ethanol, orbutanol-water, to break ternary azeotropes, or to remove amyl alcoholfrom mixtures including ethanol and water.

The pores of the porous ceramic surface modification material mayinclude open cells filled with one or more gas, may include partiallyfilled cells (e.g., partially filled with one or more solidmaterial(s)), or may include completely or substantially filled cells(e.g., completely or substantially filled with one or more liquid and/orsolid material(s)). In some embodiments, the pores are partially,substantially, or completely filled with a gas, liquid, or solidsubstance, or combinations thereof.

In some embodiments, the pores are partially filled with a firstmaterial and then partially or completely filled with a second material.In some embodiments, the second material is added as a layer of materialover partially filled pores. In some embodiments, the first material isa gas, solid, or liquid, or combination of gas, liquid, and/or solidsubstance(s). In some embodiments, the second material is a gas, solid,and/or liquid substance(s), or the environment (e.g., air). Examplesinclude, and functions thereby imparted include changes in the porosity,wicking, repellency and/or wetting behavior; changes in the composite(comprising the porous material and second material) to modifyelectrical/dielectric properties, to modify mechanical properties suchas abrasion resistance, hardness, toughness, tactile feel, elasticmodulus, yield strength, yield stress, Young's modulus, surface(compressive or tensile) stress, and/or elasticity; changes in thermalproperties such as thermal diffusivity, conductivity, thermal expansioncoefficient, thermal interface stress, and/or thermal anisotropy;modification of optical properties such as emissivity, color,reflectivity, and/or absorption coefficients; modification of chemicalproperties such as corrosion, catalysis, reactivity, inertness,compatibility, fouling resistance, ion pump blocking, microbialresistance, and/or microbial compatibility; and/or as a substrate forbiocatalysis.

In some embodiments, the first material interacts with the secondmaterial in a positive or negative synergistic manner to alter one ormore functional characteristic of the ceramic material, such as, but notlimited to, wettability, hardness, elasticity, a mechanical, electrical,piezoelectric, optical, adhesion, or thermal property, microbialaffinity or resistance, alteration of biofilm growth, catalyticactivity, permeability, aesthetic appearance, liquid repellency, and/orcorrosion resistance.

Nonlimiting materials that may be used to partially or completely fillpores include molecules capable of binding to the surface such asmolecules with a head group and a tail group wherein the head group is asilane, phosphonate or phosphonic acid, a carboxylic acid, vinyl, ahydroxide, a thiol, or ammonium compound. The tail group can include anyfunctional group such as hydrocarbons, fluorocarbons, vinyl groups,phenyl groups, and/or quaternary ammonium groups. Other ceramicmaterials can also be deposited into the pores partially or completely.Polymers may also be deposited into the pores partially or completely.Ceramic materials may include, for example, one or more oxide of zinc,aluminum, manganese, magnesium, cerium, gadolinium, and cobalt. Inaddition, ceramic materials may include any solid material which can beadded to the surface modification material, including an inorganiccompound of metal, non-metal, or metalloid atoms primarily held in ionicand covalent bonds, such as, for example, clays, silicas, and glasses.Polymers may include, for example, natural polymeric materials such ashemp, shellac, amber, wool, silk, natural rubber, cellulose, and othernatural fibers, sugars, hemi- and holo-celluloses, polysaccharides, andbiologically derived materials such as extracellular proteins, DNA,chitin. Synthetic polymers include, for example, polymers andco-polymers containing polyethylene, polypropylene polystyrene,polyvinyl chloride, synthetic rubber, phenol formaldehyde resin (orBakelite), neoprene, nylon, polyacrylonitrile. PVB, silicone,polyisobutylene. PEEK, PMMA, and PTFE.

In some embodiments, the pores are filled partially with a thincomposite polymer layer to produce a surface modification material thathas porosity and functionality provided by the polymer. In otherembodiments, the pores are filled completely with a thick polymer layerto produce a surface modification material with a thick polymer layerthat has composite properties of the porous base material and thepolymer layer. A polymer as described in the compositions hereinincludes co-polymers.

In some embodiments, the pores are partially or completely filled with alayer of material deposited over the surface of the surface modificationmaterial. In some embodiments, a layer of material is deposited thatadds one or more functional group(s) to the surface modificationmaterial, such as, but not limited to, ammonium groups (e.g., quaternaryammonium groups), alkyl groups, perfluoroalkyl groups, fluoroalkylgroups. In some embodiments, a polymer or ceramic layer is deposited. Inone embodiment, a ceramic top surface layer is deposited which is thesame or different ceramic than the ceramic of the binderless porousceramic material on the substrate. Examples of functional group(s) andfunctions thereby imparted include quaternary ammonium groups foranti-microbial functions, alkyl chains for water repellency andhydrocarbon affinity, perfluoroalkyl groups for water and oil repellantfunctions, polymers for mechanical property function, other ceramics foraesthetic functions, optoelectronic functions, or anti-corrosivefunctions.

In some embodiments, the pores are partially or completely filled with agas, liquid, or solid substance, or combinations thereof, and thecomposition further includes a layer of a top surface material over theceramic material, and the top surface material imparts one or morefunctionality, such as, but not limited to, wettability with a liquidand/or selective separation of compounds in a liquid. In certainembodiments, the top surface material is a separate material from thesubstance with which the pores are partially, substantially, orcompletely filled, and does not itself fill or intrude into the pores.In some embodiments, the top surface material interacts with thesubstance(s) in the pores. For example, the top surface material mayinteract with the substance(s) in the pores to provide one or morefunctionality, such as, but not limited to, thermal management,electrochemical reactivity modulation, and/or mechanical propertymodulation. In certain embodiments, the top surface material is thesurrounding environment with which the binderless porous ceramicmaterial is in contact.

In some embodiments, the pores are substantially or completely filledwith a polymer or with a ceramic material.

In some embodiments, a material in the pores interacts with the ceramicmaterial. Examples of such materials and functions thereby impartedinclude the oxidation of the surface modification material by ambientliquid or vapor, the condensation of minor components (e.g.,environmental pollutants), the capture or oxidation of hazardousenvironmental materials such as CO or H₂S from environmental air, and/orthe collection and retention of materials in the environment.

In some embodiments, moisture in the environment or added to the poresinteracts with a material in the pores to modify the material in thepores or the surface modification material. Examples of such materialsand functions thereby imparted include changes in wetting behavior, inoptical properties, changes in oxidation state or reactivity, changes inthe rate of evaporation, frosting, icing, or condensation.

In some embodiments, material in the pores may be designed to interactwith the ceramic material to “tune” the properties of the overallsurface. Examples of tunable properties includes, but are not limitedto, wettability, hardness, microbial resistance, catalytic activity,corrosion resistance, color, and/or photochemical activity.

In some embodiments, the ceramic surface modification material and amaterial in the pores interact in a synergistic manner, for example,enhancing or reducing at least one functionality of the surfacemodification material and/or the material in the pores, in comparison tothe functionality of the surface modification material and/or thematerial in the pores alone. In some embodiments, two or more materialsin the pores interact in a synergistic manner, for example, enhancing orreducing at least one functionality of at least one material in thepores, in comparison to the functionality of that material alone.

In some embodiments, the ceramic surface modification material isasymmetric, for example, a pore morphology that is not spherical,cylindrical, cubic or otherwise ordered as having a well-defined,relatively constant, normal distribution of surface area to volume, ascharacterized a by a ratio of the pore diameter at the first quartile tothe pore size at the third quartile as a function of the thickness ofthe binderless ceramic surface modification. In particular, the poremorphology is asymmetric about its center when compared to a spherical,cylindrical, or cubic structure. A nonlimiting example of asymmetricpores is depicted in PCT Application No. PCT/US19/39743, which isincorporated by reference herein in its entirety.

A porous ceramic surface modification material may be characterized by abroad pore size distribution that varies with distance from thesubstrate. In particular, the pore structure at a given distance fromthe substrate can be characterized locally, e.g., as described hereinand has a different characterization at a different distance. Theresulting asymmetry is determined in situ by the combination ofsubstrate, ionic mobility, processing conditions such as temperature,pressure, and concentrations. The degree of asymmetry can be furthermodified through bulk means such as mixing, agitation, electric fieldmodulation, and tank filtration, or through surface directed processmeans such as shear rates, impinging flows or surface chargemodification and modulation. The asymmetry can be determined ex situthrough a variety of means such as etching, track etching, ion beammilling, oxidation, photocatalysis, or through additional means. Theseapproaches are to refer to materials which have a narrower, or symmetricpore structures, with thickness and/or pore depth, such as zeolites,track etched membranes, or expanded PTFE membranes.

In some embodiments, the porous ceramic surface modification materialincludes mesoporous mean pore sizes that range from about 2 nm to about50 nm. In other embodiments, the mean pore sizes range from about 50 nmto about 1000 nm. In some embodiments, the binderless porous ceramicmaterial includes a mean pore diameter of about 2 nm to about 20 nm. Insome embodiments, the mean pore diameter is any of at least about 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 nm. Insome embodiments, the mean pore diameter is any of about 2 to about 5,about 4 to about 9, about 5 to about 10, about 7 to about 12, about 9 toabout 15, about 12 to about 18, about 15 to about 20, about 4 to about11, about 5 to about 9, about 4 to about 8, or about 7 to about 11 nm.

The ceramic surface modification material may include one or more metaloxide and/or metal hydroxide (and/or hydrates thereof). Non-limitingexamples of metals that may be included in the ceramic compositionsdisclosed herein include: zinc, aluminum, manganese, magnesium, cerium,copper, gadolinium, tungsten, tin, lead, and cobalt. In someembodiments, the ceramic material includes a transition metal, a GroupII element, a rare-earth element (e.g., lanthanum, cerium gadolinium,praseodymium, scandium, yttrium, samarium, or neodymium), aluminum, tin,or lead. In some embodiments, the ceramic material includes two or moremetal oxides (e.g., a mixed metal oxide) including but not limited tozinc, aluminum, manganese, magnesium, cerium, praseodymium, and cobalt.

In some embodiments, the ceramic surface modification material includes:a mixture of zinc and aluminum oxides and/or hydroxides; a mixture ofZnO and Al₂O₃, and Zn-aluminates; mixtures of materials comprisingany/all phases comprising Zn, Al, and oxygen; a mixture of manganese andmagnesium oxides and/or hydroxides; manganese oxide; aluminum oxide; amixed metal manganese oxide and/or hydroxide; a mixture of magnesium andaluminum oxides and/or hydroxides; a mixture of magnesium, cerium, andaluminum oxides and/or hydroxides; a mixture of zinc, gadolinium, andaluminum oxides and/or hydroxides; a mixture of cobalt and aluminumoxides and/or hydroxides; a mixture of manganese and aluminum oxidesand/or hydroxides; a mixture of cerium and aluminum oxides and/orhydroxides; a mixture of iron and aluminum oxides and/or hydroxides; amixture of tungsten and aluminum oxides and/or hydroxides; a mixture oftin and aluminum oxides; tungsten oxide and/or hydroxide; magnesiumoxide and/or hydroxide; manganese oxide and/or hydroxide; tin oxideand/or hydroxide; or zinc oxide and/or hydroxide.

In some embodiments, at least one metal in the ceramic material is inthe 2⁺ oxidation state.

In some embodiments, the ceramic surface modification material includesone or more oxide and/or hydroxide of zinc, aluminum, manganese,magnesium, cerium, gadolinium, and cobalt, and the substrate is aluminumor an aluminum alloy.

In some embodiments, the ceramic surface modification material issuperhydrophobic. In some embodiments, the surface modification materialis highly hydrophobic. In some embodiments, the surface modificationmaterial includes one or more functional characteristic selected fromwettability, hardness, elasticity, mechanical, electrical,piezoelectric, electromagnetic, optical, adhesion, or thermalproperties, microbial affinity or resistance, alteration of biofilmgrowth, catalytic activity, permeability, aesthetic appearance, andcorrosion resistance, in comparison to a substrate that does not includethe ceramic material.

In some embodiments, a functional material layer (e.g., top layer ofmaterial) is deposited onto the ceramic material. Examples of suchmaterials include, but are not limited to, quaternary ammonium groupsfor anti-microbial functions, alkyl chains for water repellency andhydrocarbon affinity, perfluoroalkyl groups for water and oil repellantfunctions, polymers for mechanical property function, other ceramics foraesthetic functions, optoelectronic functions, or anti-corrosivefunctions. Examples of functionalities imparted by such materialsinclude, but are not limited to,—changes in the porosity, wicking,repellency, and/or wetting behavior; changes in the composite (includingthe porous material and second material) to modify electrical/dielectricproperties, to modify mechanical properties such as abrasion resistance,hardness, toughness, tactile feel, elastic modulus, yield strength,yield stress, Young's modulus, surface (compressive or tensile) stress,tensile strength, compression strength, and/or elasticity; thermalproperties such as thermal diffusivity, conductivity, thermal expansioncoefficient, thermal interface stress, thermal anisotropy, to modifyoptical properties such as emissivity, color, reflectivity, and/orabsorption coefficients, to modify of chemical properties such ascorrosion, catalysis, reactivity, inertness, compatibility, foulingresistance, ion pump blocking, microbial resistance and/or microbialcompatibility, promotion of adhesion of subsequent material layers,and/or as a substrate for biocatalysis.

In some embodiments, the ceramic surface modification material isresistant to degradation by ultraviolet radiation, in comparison to thesubstrate material, such as a polymer or any of the substrate materialsdisclosed herein.

In some embodiments, the ceramic surface modification material includesa thickness of about 0.5 micrometers to about 20 micrometers. In someembodiments, the ceramic material includes a thickness of about 0.2micrometers to about 25 micrometers. In some embodiments, the thicknessis any of at least about 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 micrometers.In some embodiments, the thickness is any of about 0.2 to about 0.5,about 0.5 to about 1, about 1 to about 5, about 3 to about 7, about 5 toabout 10, about 7 to about 15, about 10 to about 15, about 12 to about18, about 15 to about 20, about 18 to about 25, about 0.5 to about 15,about 2 to about 10, about 1 to about 10, about 3 to about 13, about 0.5to about 15, about 0.5 to about 5, about 0.5 to about 10, or about 5 toabout 15 micrometers.

In some embodiments, the ceramic surface modification material ischaracterized by a water contact angle of about 0° to about 180°. Inother embodiments, the water contact angle is less than about 30degrees. In other embodiments the water contact angle is greater thanabout 150 degrees.

In some embodiments, the ceramic surface modification material includesa surface area of about 1.1 m² to about 100 m² per square meter ofprojected substrate area. In some embodiments, the ceramic materialincludes a surface area of about 10 m² to about 1500 m² per square meterof projected substrate area. In some embodiments, the surface area isany of at least about 10, 50, 100, 150, 200, 250, 300, 350, 400, 450,500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100,1150, 1200, 1250, 1300, 1350, 1400, 1450, or 1500 m² per square meter ofprojected substrate area. In some embodiments, the surface area is anyof about 10 to about 100, about 50 to about 250, about 150 to about 500,about 250 to about 750, about 500 to about 1000, about 750 to about1200, about 1000 to about 1500, about 70 to about 1000, about 150 toabout 800, about 500 to about 900, or about 500 to about 1000 m² persquare meter of projected substrate area.

In some embodiments, the ceramic material includes a surface area ofabout 15 m² to about 1500 m² per gram of ceramic material. In someembodiments, the surface area is any of at least about 15, 50, 100, 150,200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850,900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, or1500 m² per gram of ceramic material. In some embodiments, the surfacearea is any of about 15 to about 100, about 50 to about 250, about 150to about 500, about 250 to about 750, about 500 to about 1000, about 750to about 1200, about 1000 to about 1500, about 50 to about 700, about 75to about 600, about 150 to about 650, or about 250 to about 700 m² pergram of ceramic material.

Substrates

The substrate on which one or more coating or surface modificationmaterials as described herein are applied or deposited may be composedof any material suitable for the structural or functionalcharacteristics, or functional application of use, for example, in adevice, such as a heat exchanger. In some embodiments, the substrate isaluminum or contains aluminum (e.g., an aluminum alloy), a ferrousalloy, zinc, a zinc alloy, copper, a copper alloy, a nickel alloy,nickel, a titanium alloy, titanium, a cobalt-chromium containing alloy,glass, a polymer, a co-polymer, a natural material (e.g., a naturalmaterial containing cellulose), or a plastic.

In some embodiments, the substrate includes a metal, and the primarymetal in a ceramic surface modification material as described herein isdifferent than the primary metal in the substrate. A primary metal is ametal that is at least about 50%, 60%, 70%, 80%, 90%, or 95% of thetotal metal in the substrate or the ceramic material, e.g., asdetermined by x-ray diffraction on an atomic metals basis. Examples ofsubstrate primary metals include, but are not limited to, aluminum,iron, copper, zinc, nickel, titanium, and magnesium. Examples of ceramicprimary metals include, but are not limited to, zinc, aluminum,manganese, magnesium, cerium, copper, gadolinium, tungsten, tin, lead,and cobalt.

In some embodiments, the substrate includes a metal that is able toreact (e.g., dissolve) under reaction conditions that allow for localdissolution of the substrate metal, and the substrate metal isincorporated into a substrate modification material, such as a ceramicmaterial, e.g., a binderless porous ceramic material. For example, analuminum substrate may provide aluminum (e.g., Al²⁺) that isincorporated into ceramic material as the ceramic material is depositedon the substrate.

The following examples are intended to illustrate, but not limit, theinvention.

EXAMPLES

The substrates or assembles to which the coating is applied typically gothrough a process starting with (a) surface preparation or cleaning,followed by (b) a conversion or primer step, (c) a structured ceramicdeposition, and (d) the deposition of another ceramic layer, conversionof the deposited structured ceramic layer, or deposition of a monolayer,paint, oil or resin. In some cases, some of the steps can be bypassed togive a different outcome.

(a) Surface preparation and cleaning step: In the examples below, thesurface was prepared as follows. The metallic substrates or assemblieswere pot cleaned or wiped with isopropyl alcohol (IPA) and a towel toremove any residual oils. Next, the parts were submerged in a causticetch bath at pH>10 at a nominal room temperature of 20° C. until adarkening of the surface was observed, or about 15 minutes. Thesubstrates or assemblies were then rinsed in water to remove anyresidual caustic or loosely adhered material. Next, the parts weresubmerged in a nitric acid solution with pH below 3 and temperature of20° C. to remove smut, etch reaction products, intermetallic and surfaceoxide, or to pickle the substrate, revealing a clean surface. Othersurface preparation techniques that result in a clean surface areappropriate are applicable. Polymeric and cellulosic substrates were potcleaned or wiped with isopropyl alcohol on a towel to remove anyresidue.

(b) Conversion coating or primer: Conversion coatings and/or primers inthe following examples are considered continuous unless otherwisedescribed. Selective coverage was carried out through a partial chemicalexposure and/or through the use of masking agents. Conversion coatingsor primers consist of films generated through a chemical orelectrochemical conversion of the substrate, resulting in a thin filmwith low porosity when compared to structural ceramic deposition layersdescribed below. Conversion coatings are typically either oxides,phosphates, or chromates and carried out at low pH. Application methodsinclude immersion plating, which can in some cases include theapplication of electrical bias, or spraying chemical solutions on thesubstrates to be coated. Inorganic materials such as aqueous acidicchromium (III) phosphate with other metals and anionic reactants tomodify the solution pH. Solutions consisting of insoluble solidmaterials were heated from 40° C.-100° C. with solution/substratecontact from 1 to 90 minutes. Surfactants can be added to enhance thefilm composition or substrate conversion reaction rate. The surface ofthe exposed substrate reacts, forming a dense layer, wherein theconversion of the substrate surface provides a diffusion barrier tolimit further reaction. A thermal stabilization step can be used toaccelerate the formation of conversion layer.

Conversion layers or primers were dried prior to introduction ofstructural ceramic deposition methods or depositedmonolayer/paint/oil/resin layers unless otherwise indicated. Processtimes between application of conversion layers and subsequent processingwas less than 24 h unless otherwise noted.

(c) Structured or porous ceramic deposition: Structured ceramicdepositions in the following examples are considered continuous unlessotherwise described. Selective coverage was carried out through apartial chemical exposure and/or through the use of masking agents. Thesubstrates or assemblies were then placed into the structured ceramicdeposit bath containing 20-500 mM of metal nitrate and a similar amountof an amine (such as ethylene diamine, hexamethylenetetramine, or urea),and were allowed to react prior to the substrate insertion at a reactiontemperature of 30-90° C. The assemblies were maintained in the bathuntil the turbidity dropped below 100 NTU or for about 5 minutes toabout 90 minutes. The substrates or assemblies were removed, drained,rinsed and placed into an oven to dry and/or calcine at approximately100° C.-800C for several hours. The parts were then allowed to cool toroom temperature. Structural ceramics were dried prior to depositedmonolayer/paint/oil/resin layers unless otherwise indicated.

(d) Deposited monolayer/paint/oil/resin—continuous/selective coveragewith/without gradient: Deposited monolayer/paint/oil/resin in thefollowing examples are considered continuous unless otherwise described.Selective coverage was carried out through a partial contact and/orthrough the use of masking agents. Structural ceramics created in (c)were dried prior to a post processing step, such as a conversion of thedeposited ceramic or deposition of a second ceramic that partially orcompletely filled the porous interconnected ceramic network with asecond material, unless otherwise indicated. Substrate temperatures weretypically maintained at room temperature, and deposition solutions weretypically maintained at ambient room temperatures unless otherwisenoted. Deposited monolayer/paint/oil/resin consisted of materialsapplied to the upper surface layer by painting, spraying, immersion,wicking, vapor phase condensation, and may include thermal or catalytictreatment to expedite drying of the materials and/or increase chemicalor mechanical adhesion to the upper surface layers. These processingsteps are described in additional detail in each Example as needed.

Example 1. A₁-B₁₁—Conversion Coating+Selective Coverage Paint

A heat exchanger (HX) is completely coated in a conversion coating, suchas trivalent chromium process (TCP) via an immersion or spray coatingprocess. The manifolds and brazing joints of the manifolds and tubes aresubsequently painted via a partial dip or spray coating a particularlocation on the part. In this particular case, the complete coil istotally immersed to apply a conversion coating. In a subsequent step,the manifolds of the heat exchanger are sequentially dipped into a paintbath. The conversion area of the coil will have corrosion protectionwhile maintaining its heat transfer coefficient while the paintedmanifolds and manifold-tube joints will have an extra protective layerfrom corrosion.

Example 2. A₁-B₁₀—Conversion Coating+Gradient Paint

A HX is completely coated in a conversion coating, such as TCP, appliedto the entire HX via an immersion step. This process step is followed bya complete coating of a paint that is thicker at the bottom of the HXthan the top, which is applied via dip coating and encouraging the paintto drain in a preferred orientation resulting in a thicker layer in thatorientation. A complete spraying, with additional passes of the sprayerin the desired thicker location would be similar. The regions of thickerpaint coating will have an increased corrosion resistance. The top ofthe HX requires less paint due to the lower exposure time of accumulatedliquid, thus lowering production cost of having a uniform thicknessacross the entire HX while providing the same amount of corrosionprotection that also reduces the thermal HX losses by minimizing theapplication of paint to primarily areas that need protection and/orlimiting material applied to critical heat exchange surfaces.

Example 3. A₁-B₁₀—Conversion Coating+Gradient Paint

A HX is completely coated in a conversion coating, such as TCP, followedby a complete coating of a paint that is thicker at the bottom of the HXthan the top, which is applied in sequential dip coating steps with asequentially shallower immersion depth. As water accumulates at thebottom of the coil during use, the thicker paint coating at the bottomhas an increased corrosion resistance. The top of the HX requires lesspaint due to the lower exposure time of accumulated liquid, thuslowering production cost of having a uniform thickness across the entireHX while providing the same amount of corrosion protection.

Example 4. A₁-B₁₂—Conversion Coating+Selective Coverage Gradient Paint

An aluminum containing marine alloy as may comprise the hull of a shipis completely coated in a conversion coating, such as TCP. The alloy isthen coated with a corrosion resistant paint via contact or spraypainting. The paint is applied in multiple layers in the regions thatrequire additional corrosion protection, such as near the waterline andat the bottom of the hull, to provide scratch protection. The thickerpaint layers add more corrosion resistance to the areas most exposed tocorrosive environments.

Example 5. A₁-B₆—Primer+Gradient Structured Ceramic

A fin-tube HX coil is completely coated with a primer that has corrosionresistance properties, such as TCP or similar phosphate coating. The HXis then completely modified with a ceramic surface modification in animmersion deposition system. The deposition fluids velocities aremodified at different areas of the coil changing the composition of thestructured ceramic in the regions with changed velocities. This approachmay be used to induce a pore size gradient across the coil. The varyingpore size creates variable wicking patterns that can pull water awayfrom areas prone to corrosion.

Example 6. A₁-B₇—Primer+Selective Coverage Structured Ceramic

A brazed aluminum HX is completely coated with a ceramic surfacemodification primer that has corrosion resistance properties, such asTCP or similar phosphate coating. The manifolds and manifold-tubebrazing joints are then coated in a multilayer structured ceramic thatprevents corrosive solutions from reaching the HX surfaces at the mostvulnerable areas. The structured ceramic material also modifies themanner in which rain, condensate and other applied liquids are retainedon the surface. As an example, a structured ceramic layer may have a lowcontact angle, leading to a thinner liquid layer at the appliedlocations which would lead to more rapid drying of the surface.

Example 7. A₁-B₆—Primer+Selective Coverage Gradient Structured Ceramic

A HX is completely coated with a primer or conversion coating that hascorrosion resistance properties, such as TCP or ceria. The upper half ofthe HX is then modified with a structured ceramic surface modificationduring which the shear rate is varied to create a gradient in pore sizetowards the top of the HX. The gradient of pore sizes causes water towick towards the top of the HX, away from the most vulnerable areas ofHX.

Example 8. A₁-B₅-C₉-D₁₁—Primer+Structured Ceramic+Functional MaterialLayer+Selective Coverage Paint)

A brazed aluminum HX is completely coated with a primer coating followedby a structured ceramic surface modification and an optional functionalmaterial layer such as steric acid to provide a surface energymodification. The manifolds and manifold-tube joints are then paintedvia spray or dip coating to provide additional corrosion protection oran aesthetic look. The main portion of the coil that has had afunctional material layer applied has a high contact angle and rejectswater from standing on the surface and increases thermal capacity, whilethe less functional areas that are prone to corrosion are protected bythe corrosion resistant paint.

Example 9. A₁-B₅-C₁₀—Conversion Coating+Structured Ceramic+GradientFunctional Material Layer

A marine alloy as may comprise the hull of a ship is completely coatedin a conversion coating, such as TCP, followed by a complete coatingwith a structured ceramic surface modification. The hull is thenmodified with a functional material layered to create a superhydrophobicsurface. The functional material layer will be applied such that the bowof the hull is more hydrophobic than the stern. The superhydrophobicsurface allows the ship to reduce drag more effectively and/or be moredurable at the points of highest water shear rate during operation,while the TCP and ceramic surface modification protects the rest of thehull from the corrosion of sea water.

Example 10. A₁-B₅-C₁₁—Conversion Coating+Structured Ceramic+SelectiveCoverage Functional Material Layer

An HX is completely coated with a conversion coating, followed by astructured ceramic surface modification. The bottom half of the coil isthen functional material layered to create a superhydrophobic surface.The bottom half of the coil rejects water condensation and prevent theaccumulation of water at manufacturing joints and design features suchas the manifold-tube joints, fin-tube joints, or louvers. With thedecrease in water accumulation at the most vulnerable areas of the coil,the most vulnerable areas of the coil to corrosion are protected.

Example 11. A₁-B₅-C₁₂—Conversion Coating+Structured Ceramic+SelectiveCoverage Gradient Functional Material Layer

An HX is completely coated with a conversion coating, followed by astructured ceramic surface modification. The coil is then coated in acorrosion resistant functional material layer that is thicker on theoutside facing side of the HX than the inside facing side. This protectsthe outside (e.g., environmental or airstream) facing side of the HXfrom corrosive environments (acid rain, cat urine, etc. or contaminantsin the airstream). while the inside facing side (e.g., side that is notexposed to environmental conditions or airstream) exhibits a limiteddecrease in heat transfer performance. Overall, the pressure drop isreduced relative to a uniform thickness coverage.

Example 12. A₃Selective Coverage Conversion Coating

A brazed aluminum HX is partially coated with a conversion coating onthe manifolds and brazing joints of the manifolds and tubes applied viaselective immersion into a process bath. The coated areas preventcorrosion in the areas that are most susceptible to corrosion.

Example 13. A₅-B₉-C₁₁—Structured Ceramic+Functional MaterialLayer+Selective Coverage Paint

A HX is completely coated in a structured ceramic surface modification,followed by a functional material layer that enhances hydrophobicity tocreate a superhydrophobic surface. The manifolds and brazing joints ofthe manifolds and tubes are painted to create a more corrosion resistantarea of the coil. The superhydrophobic area of the coil rejects wateraccumulation during use while the painted manifold and manifold-tubejoints protect the more vulnerable areas from corrosion.

Example 14. A₅-B₁₀—Structured Ceramic+Gradient Functional Material Layer

An HX is completely coated with a binderless structured ceramic surfacemodification. The coil is then coated in a corrosion resistantfunctional material layer that is thicker on the outside facing side ofthe HX than the inside facing side. This protects the outside facingside of the HX from corrosive environments (acid rain, cat urine, etc.),while the inside facing side exhibits limited decrease in heat transferperformance. Overall the pressure drop is reduced relative to a uniformthickness coverage.

Example 15. A₅-B₁₁—Structured Ceramic+Selective Coverage FunctionalMaterial Layer

A brazed aluminum heat exchanger was completely coated with a binderlessstructured magnesium oxide ceramic surface modification that wasdeposited in a 25 to 100 mM aqueous solution of magnesium nitrate and asimilar amount of hexamethylenetetramine at a temperature of about 50°C. to 80° C. for a time period of about 15 to 90 minutes. The coil wasthen calcined at a temperature of about 400° C. for about 1 hour. Thecoil was allowed to cool and was then immersed for a second time in a 25to 100 mM aqueous solution of magnesium nitrate and a similar amount ofhexamethylenetetramine at a temperature of about 50° C. to 80° C. for atime period of about 15 to 90 minutes. The coil was then calcined asecond time at a temperature of about 400° C. for about 1 hour. The coilwas then cooled and partially immersed in a solution containing a roomtemperature vulcanizing (RTV) silicone at a concentration between 0.5 wt% and 10 wt %, preferably about 2 wt % in tert-butyl acetate. The heatexchanger was immersed such that approximately half of the heatexchanger was in the solution, and approximately half of the heatexchanger was in the vapor space above the solution. The heat exchangerwas immersed for about 10 to 300 minutes, preferably about 30 minutes.The heat exchanger was then placed in air for 24 to 72 hours where theRTV silicone formed a superhydrophobic functional layer on the surfaceof the heat exchanger with a contact angle of >120°. Theunfunctionalized portion of the heat exchanger was then placed in anaqueous solution containing an aminoethylaminopropylsilsesquioxane at aconcentration of 0.1 wt % to 10 wt %, preferably about 5 wt %. The heatexchanger was immersed for 10 minutes to 240 minutes, preferably about30 minutes. The heat exchanger was thoroughly rinsed with de-ionizedwater to remove any remaining solution from the surface and annealed inan oven at an temperatures of 90° C. and 140° C., preferably about 110°C., for 30 minutes to 300 minutes, preferably about 60 minutes. Thesilsequioxane functionalized structured ceramic was hydrophilic and hada water contact angle of <60°.

On the finished heat exchanger, there was an interface between the RTVfunctionalized ceramic surface and the silsequioxane functionalizedceramic surface. On the RTV side of this interface, water dropletsbeaded up and rolled off the surface. On the silsequioxanefunctionalized ceramic surface, water droplets wetted the surface andspread out along the surface.

Example 16. A₅-B₁₁—Structured Ceramic+Selective Coverage FunctionalMaterial Layer

A HX was fully coated with a binderless structured ceramic surfacemodification comprising magnesium and aluminum oxides/hydroxides asdescribed above The HX was dipped in a 25 to 75 mM aqueous solution ofmagnesium nitrate with a similar quantity of hexamethylenetetramine at atemperature of about 60° C. to 80° C. for a time period of about 30 to120 minutes. The coil was then calcined at a temperature of about 400°C. to 600° C. for about 1 hour. A subsequent treatment was carried outby immersion of half of the coil in a bath containing a functionalmaterial layer chemical. The functional material, hexadecylphosphonicacid, layer was applied to the bottom half of the coil. The functionalmaterial layer created a superhydrophobic surface on the bottom half ofthe coil.

The heat exchanger was then fitted into a controlled air stream andchilled below the dew point of the air stream using chilled glycol. Theupper half of the heat exchanger which contained just the structuralceramic layer generated condensate during the testing which was retainedin the heat exchanger body. The lower portion of the heat exchanger thatwas treated with a functional material layer that resulted insuperhydrophobic surface (contact angle>150 degrees) conditions resultedin condensation demonstrating heat exchange but the condensate was notretained in the heat exchanger body during wind tunnel testing whereincondensation was occurring.

Example 17. A₅-B₁₂—Structured Ceramic+Gradient Functional Material Layer

A brazed aluminum heat exchanger was completely coated with a binderlessstructured magnesium oxide ceramic surface modification that wasdeposited in a 25 to 75 mM aqueous solution of magnesium nitrate and asimilar quantity of hexamethylenetetramine at a temperature of about 60°C. to 80° C. for a time period of about 30 to 90 minutes. The coil wasthen calcined at a temperature of about 400° C. to 600° C. for about 1hour. The coil was allowed to cool and immersed a second time in a 25 to100 mM aqueous solution of magnesium nitrate and a similar amount ofhexamethylenetetramine at a temperature of about 50° C. to 80° C. for atime period of about 15 to 90 minutes. The coil was then calcined asecond time at a temperature of about 400° C. for about 1 hour. Twodifferent solutions were created, one was a solution containing a roomtemperature vulcanizing (RTV) silicone at a concentration of 0.5 wt % to10 wt %, preferably 2 wt %, in tert-butyl acetate. The other solutionwas an aqueous solution containing aminoethylaminopropylsilsesquioxaneat a concentration of 0.1 wt % to 10 wt %, preferably about 5 wt %. Theheat exchanger was placed in a spray chamber and the solutions were eachsprayed in a fashion such that one side of the heat exchanger wassprayed with the RTV solution and the other side was sprayed with theaminoethylaminopropylsilsesquioxane solution for 1 minute to 30 minutes,preferably about 5 minutes. The heat exchanger was annealed in an ovenat a temperatures of 90° C. to 140° C., preferably about 110° C., for 30minutes to 300 minutes, preferably about 60 minutes. The silsequioxanefunctionalized structured ceramic was hydrophilic and had a watercontact angle of <60° while the RTV functionalized structured ceramicwas hydrophobic and had a contact angle of >120°

On the finished heat exchanger, there was a gradient interface betweenthe RTV functionalized ceramic surface and the silsequioxanefunctionalized ceramic surface as a result of the spray pattern. Whenwater was sprayed onto the heat exchanger, the water droplets bouncedoff of the hydrophobic functionalized surface and wicked into the finpack on the hydrophilic functionalized surface. As water condenses or isintroduced to the surface, it can flow from hydrophobic areas tohydrophilic areas and improve the heat transfer of the surface

Example 18. A₅-B₁₂—Structured Ceramic+Selective Coverage GradientFunctional Material Layer

An aluminum panel was modified with a structured ceramic material ofmanganese and aluminum oxides that was deposited in a 50 to 150 mMaqueous solution of manganese nitrate and a similar quantity ofhexamethylenetetramine at a temperature of about 70° C. to 80° C. for atime period of about 30 to 120 minutes. The panel was then baked at atemperature of about 400° C. for about 1 hour. The panel was thenselectively coated with sealant materials such as a drying oils, such astung oil or linseed oil, or waxes, such as paraffin wax or bees wax,such that about 10% of the top of the panel was not covered with the oilor wax. This allowed for electrical contact to be made to the sample andenables use as an electrode for a battery or capacitor.

Example 19. A₆—Gradient Structured Ceramic

A HX coil was completely coated with a magnesium based structuredceramic surface modification comprising magnesium and aluminumoxides/hydroxides. The surface was deposited in a 25 to 75 mM aqueoussolution of magnesium nitrate and a similar quantity ofhexamethylenetetramine at a temperature of about 60° C. to 80° C. for atime period of about 30 to 90 minutes. The coil was then calcined at atemperature of about 400° C. to 600° C. for about 1 hour. The shear rateof the reacting chemical mixture was varied at different areas adjacentto and along the coil, which created a gradient in thickness of thesurface modification. A heat exchanger was treated to apply a structuredceramic as described above. A recirculation system moved the processingliquid from the base of the immersion tank to a pump and filter toremove suspended solids from the stream. The liquid was returned to theimmersion tank containing a heat exchanger through a liquid eductor,which focused and amplified the liquid motion adjacent to the eductor.The recirculated fluid was directed to the midpoint of one manifold, andalong the length of the heat exchanger. The areas of higher shear ratehad an increased amount of the ceramic modification with varying poresize. The increased deposition levels were demonstrated through a visualobservation of the color of the material along the manifold and heatexchanger surface. Regions of increased deposit were seen to be morewhite in color than the remainder of the heat exchanger, which had agrey appearance. X-ray fluorescence (XRF) measurements confirmed thatthe areas that appeared whiter had a higher amount of the magnesium andaluminum oxide surface modification compared to adjacent areas thatappeared darker in color. These regions with thicker structural layerscan provide additional protection against corrosive elements from thesurrounding environment.

Example 20. A₆—Gradient Structured Ceramic

A HX coil is completely coated with a structured ceramic surfacemodification. The coil is placed in a 25-75 mM aqueous solution ofmagnesium nitrate and a similar quantity of hexamethylenetetramine at atemperature of about 60° C. to 80° C. for a time period of about 30 to90 minutes. The coil was then calcined at a temperature of about 400° C.to 600° C. for about 1 hour. During processing, the temperature,concentration, and shear rates are varied to create a denser structurewith smaller pore sizes closer to the fins and less dense structure withincreased pore sizes in the ceramic deposit further from the fins. Thegradient of the ceramic structure with surface modification thicknessenhances water wicking properties at the outer areas of the ceramicdeposit to decrease drying time, while the increased density and smallerporosity toward the fin surface of the HX minimizes the quantity ofwater from contacting the substrate. This enhances drying time and onsetof frost, while inhibiting corrosion of the surface.

Example 21. A₆-B₉—Gradient Structured Ceramic+Functional Material Layer

A HX is completely coated with a magnesium oxide based structuredceramic surface modification. The coil is placed in a 25 to 75 mMaqueous solution of magnesium nitrate and a similar quantity ofhexamethylenetetramine at a temperature of about 60° C. to 80° C. for atime period of about 30 to 90 minutes. The coil is then calcined at atemperature of about 400° C. to 600° C. for about 1 hour. The shear rateis varied at different areas along the coil, creating a gradient of poresize and altering the topography of the ceramic surface. The HX is thenuniformly treated with a functional material layer to create asuperhydrophobic surface such as perfuloralkylsilanes, fatty acids, oralkyl phosphonic acids. The gradient created by the ceramic modificationcreates areas that provide droplet rejection characteristics to controlthe wettability of certain areas of the coil. These areas of dropletrejection can be focused on areas known to be more vulnerable tocorrosion related failures.

Example 22. A₆-B₁₀—Gradient Structured Ceramic+Gradient FunctionalMaterial Layer

A brazed aluminum heat exchanger is immersed into an immersion tank andthe part is agitated by oscillation in a direction orthogonal to theprimary airflow direction during operation. The part motion results in agreater deposition of a structured ceramic layer at the leading andtrailing edges when the primary operation airflow directions areconsidered than in the central section of the heat exchanger body. Thisgreater deposition rate increases the thickness of material at theleading and trailing edges providing protection. The part is thensubsequently treated through the application of a functional materiallayer on the leading edge (when considering the airflow direction) toprovide additional wear and abrasion protection on the leading edge.

Example 23. A₆-B₁₁—Gradient Structured Ceramic+Selective CoverageFunctional Material Layer

An aluminum alloy as may comprise the body of an aircraft is coated witha structured ceramic surface modification. The shear rate is varied suchthat the front facing portions of the wings, propeller blades,horizontal stabilizers, and rudder have increased variability intopography. The front facing portions of the wings, propeller blades,horizontal stabilizers, and rudder are then treated selectively with afunctional material layer. The increased variability in topography fromthe ceramic surface modification results in the functional materiallayer possessing a droplet rejection property, which serves to preventice formation on the most vulnerable areas of the aircraft. The overallweight of the aircraft is reduced through selective protection.

Example 24. A₆-B₁₂—Gradient Structured Ceramic+Selective CoverageGradient Functional Material Layer

A HX is completely coated with a structured ceramic surfacemodification. The shear rate is varied such that the top of the HX has athicker ceramic layer than the bottom. The bottom half of the coil isthen painted via dip or spray painting with a focus on the manifold-tubebrazing joints. The thicker areas of the paint protect the morevulnerable areas of the coil while the thicker ceramic layer wicks wateraway from the underlayers of the paint so water or other corrosivesolutions cannot undercut the paint.

Example 25. A₇—Selective Coverage Structured Ceramic

A steel-aluminum heat exchanger was coated with a structured ceramicsurface modification that has corrosion resistance properties and thatwas also preferentially deposited on the aluminum fins but not the steeltubes. The coil was placed in a 25 to 75 mM aqueous solution ofmagnesium nitrate and a similar quantity of hexamethylenetetramine at atemperature of about 60° C. to 80° C. for a time period of about 30 to90 minutes. The coil was then calcined at a temperature of about 400° C.to 600° C. for about 1 hour. The structured ceramic included zinc andaluminum oxides/hydroxides. The ceramic surface was hydrophilic andwicked water from the steel tube to the aluminum fins to allow betterwater management and improve the heat exchanger's performance, whileprotecting the steel tubes from corrosion.

Example 26. A₇—Selective Coverage Structured Ceramic

An aluminum panel was selectively protected (masked) in a pattern. Thepanel was masked with silicone tape in a desired pattern and the maskedpanel was deposited with a structured ceramic. The masked surface wasplaced in a 25 to 75 mM aqueous solution of magnesium nitrate and asimilar quantity of hexamethylenetetramine at a temperature of about 60°C. to 80° C. for a time period of about 30 to 90 minutes. The maskingfrom the panel was removed and the panel was then calcined at atemperature of about 400° C. to 600° C. for about 1 hour. On removal ofthe masking, a patterned structural ceramic remained, allowing forselective moisture collection (wicking) patterns or moisture removal(draining) patterns. The part also contained a region of bare metaladjacent to the structured layer which may be used for electricalcontact with the substrate.

Example 27. A₇—Selective Coverage Structured Ceramic

An aluminum panel was selectively protected (masked) in a pattern. Thepanel was masked in a pattern with a permanent marker containing a dyepigment, a resin, and organic solvents. The masked panel wassubsequently coated in a binderless structured ceramic surfacemodification that included zinc and aluminum oxides/hydroxides. Themasked panel was deposited in a 25 to 75 mM aqueous solution of zincnitrate and a similar quantity of hexamethylenetetramine at atemperature of about 60° C. to 80° C. for a time period of about 30 to90 minutes. The panel was then calcined at a temperature of about 400°C. to 600° C. for about 1 hour. During thermal treatment, the dyepigment, resin and organic solvents in the mask were vaporized andoxidized, leaving a bare aluminum substrate. Structural ceramicremained, allowing for selective moisture collection (wicking) patternsor moisture removal (draining) patterns. The part also contained aregion of bare metal adjacent to the structured layer which may be usedfor electrical contact with the substrate.

Example 28. A₇—Selective Coverage Structured Ceramic

An aluminum panel was selectively protected (masked) in a pattern. Thepanel was masked in a desired pattern with a permanent marker containinga dye pigment, a resin, and organic solvents. The masked panel wassubsequently coated in a binderless structured ceramic surfacemodification that included zinc and aluminum oxides/hydroxides. Themasked panel was deposited in a 25 to 75 mM aqueous solution of zincnitrate and a similar quantity of hexamethylenetetramine at atemperature of about 60° C. to 80° C. for a time period of about 30 to90 minutes. The panel was then calcined at a temperature of about 400°C. to 600° C. for about 1 hour. During thermal treatment, the dyepigment, resin and organic solvents in the mask were vaporized andoxidized, leaving a bare aluminum substrate. The structural ceramic wasthen modified with a hexadecylphosphonic acid functional layer which wasselective for the ceramic material. This resulted in a superhydrophobicstructured ceramic surface near a more hydrophilic bare aluminumsurface. The contact angle of water of the functionalized structuredceramic surface was higher than the contact angle for the bare aluminumpanel.

Example 29. A₇ B₉—Selective Coverage Structured Ceramic+ContinuousFunctional Material

An aluminum panel was selectively protected (masked) in a pattern. Thepanel was masked with polyimide tape in a desired pattern and the maskedpanel was subsequently coated in a structured binderless ceramic surfacemodification that included magnesium and aluminum oxides/hydroxides. Thepanel was deposited in a 25 to 75 mM aqueous solution of magnesiumnitrate and a similar quantity of hexamethylenetetramine at atemperature of about 60° C. to 80° C. for a time period of about 30 to90 minutes. The panel was then calcined at a temperature of about 400°C. to 600° C. for about 1 hour. The adhesive in the polyimide tape wasvaporized and re-deposited on the surface of the metal, forming asuperhydrophobic structured ceramic. Upon removal of the masking, therewas a difference in the contact angle between the structured ceramicsurface coated with a functional layer and the aluminum surface coatedwith the same functional layer, due to the presence of the structuredceramic layer.

Example 30. A₇—Selective Coverage Structured Ceramic

An aluminum panel is selectively protected (masked) in a pattern. Themasked panel is subsequently sprayed or showered to deposit a ceramicsurface modification on unmasked surfaces. On removal of the masking, apatterned structural ceramic remains comprising magnesium and aluminumoxides/hydroxides, allowing for selective moisture collection (wicking)patterns or moisture removal (draining) patterns. The spray or showerapplication of the ceramic material is configured to provide additionaldeposit coverage to preferential draining locations.

Example 31. A₇-B₁₁—Selective Coverage Structured Ceramic+SelectiveCoverage Paint

An aluminum panel was selectively protected (masked) in a pattern usinga Kapton (polyimide) adhesive tape. The masked panel was subsequentlycoated with a binderless structured ceramic surface modification thatincluded magnesium and aluminum oxides/hydroxides, as described inExample 29. Silicone tape has also been successfully used on aluminumpanels and HX materials. On removal of the masking, a patternedstructural ceramic remained. The patterned panel was then dipped in ananodic dye in which the patterned structural ceramic preferentiallyabsorbed the pigment of the dye, changing the color of the structureddeposit sections only.

Example 32. A₇-B₉—Selective Coverage Structured Ceramic+FunctionalMaterial Layer

A stainless steel-aluminum heat exchanger was coated with a structuredceramic surface modification that was preferential to the aluminum finsbut not the stainless steel or copper tubes. The heat exchanger wascoated with a structured ceramic surface by dipping it deposited in a 25to 75 mM aqueous solution of magnesium nitrate and a similar quantity ofhexamethylenetetramine at a temperature of about 60° C. to 80° C. for atime period of about 30 to 90 minutes. The coil was then calcined at atemperature of about 400° C. to 600° C. for about 1 hour. The heatexchanger was then functionalized with a monolayer material by dippingit into a dilute solution (0.1-1% by mass) of hexadecylphophonic acid,perfluoroalkylsilanes, fatty acids, or alkyl silanes, to create asuperhydrophobic surface on the aluminum fins. The superhydrophobicfunctional material layer on the fins resulted in droplet rejectionproperties, which prevented water accumulation on the fins and improvedthe heat exchanger's performance compared to a similar uncoated heatexchanger. The surface properties also provided a protective layer fromcorrosion. Because the ceramic surface modification material selectivelymodified the aluminum fins, less raw materials were used than if thesurface modification were applied to both the fins and tubes, resultingin a cheaper process.

Example 33. A₇-B₉—Selective Coverage Structured Ceramic+FunctionalMaterial Layer

An aluminum panel was selectively protected (masked) in a pattern. Thepanel was masked with polyimide tape in a desired pattern and the maskedpanel was deposited with a structured ceramic material, and thepolyimide material was not removed prior to exposure to elevatedtemperatures. The panel was placed in a 25 to 75 mM aqueous solution ofmagnesium nitrate and a similar quantity of hexamethylenetetramine at atemperature of about 60° C. to 80° C. for a time period of about 30 to90 minutes. The panel was then calcined at a temperature of about 400°C. to 600° C. for about 1 hour. The resulting panel had a patternedstructural ceramic that included magnesium and aluminumoxides/hydroxides and the regions that contained a structural ceramiclayer were significantly more hydrophobic than the patterned (covered)areas that did not contain structured ceramic. The masked regions diddemonstrate a contact angle difference relative to an untreated panel.

Example 34. A₇-B₁₁—Selective Coverage Structured Ceramic+SelectiveCoverage Functional Material Layer

A stainless steel-aluminum heat exchanger is coated with a structuredceramic surface modification that is preferential to the aluminum finsbut not the stainless steel tubes. A functional material is thenselectively layered onto the ceramic material only due to its chemicalbonding selectivity to the ceramic relative to the steel. This creates asuperhydrophobic surface on the fins, preventing water from accumulatingon the fins, which decrease air flow through the fin pack of the heatexchanger, while maintaining the natural corrosion resistance of theunmodified stainless steel.

Example 35. A₈—Selective Coverage Gradient Structured Ceramic

A stainless steel-aluminum heat exchanger is coated with a structuredceramic surface modification that is preferential to the aluminum finsbut not the stainless steel tubes. The fins are processed longer on oneside than the other. This creates a gradient of porosity across thealuminum fins.

Example 36. A₈—Selective Coverage Gradient Structured Ceramic

A stainless steel-aluminum heat exchanger is coated with a structuredceramic surface modification that is preferential to the aluminum finsbut not the stainless steel tubes. The fins have a surface roughness dueto the manufacturing process and grain boundaries wherein the structuredceramic material is deposited thicker due to the selective targeting ofthese areas to mitigate corrosion.

Example 37. A₈—Selective Coverage Gradient Structured Ceramic

A series of 3003 aluminum Q-panel test substrates were coated with abinderless structured ceramic surface modification comprising magnesiumand aluminum oxides/hydroxides and subjected to different flowconditions during the deposit process, as shown in Table 1. The panelswere placed in a 25 to 75 mM aqueous solution of magnesium nitrate and asimilar quantity of hexamethylenetetramine at a temperature of about 60°C. to 80° C. for a time period of about 30 to 90 minutes. The panelswere calcined at a temperature of about 400° C. to 600° C. for about 1hour.

As shown in Table 1, the velocities, deposit masses and resultingconcentrations are relative to the base case, shown in the second row,with the velocity setpoint and resulting mass and concentrations beingthe reference. The changing flow conditions resulted in changes to theamount of mass deposited as well as the composition of the deposit. Allother process parameters, temperatures, compositions, materials remainedunchanged. This example illustrates that a processing parameter can beused to generate gradients in the structural properties of thebinderless ceramic surface layer to provide useful benefit.

TABLE 1 Velocity Resulting deposit Resulting deposit condition massconcentration 0.04 V 0.35 M 0.33 C 1.0 V 1.0 M 1.0 C 4.25 V 1.53 M 1.67C 9.75 V 1.15 M 1.67 C

Example 38. A₈—Selective Coverage Gradient Structured Ceramic

An aluminum heat exchanger is coated with a structured ceramic surfacemodification and subjected to changing process conditions duringprocessing. The temperature of the processing bath is reduced during theprocessing, resulting in a change in composition of the structural layeras a function of deposit thickness, as compared to a heat exchangerprocessed at a uniform temperature.

Alternatively, the chemical composition of the processing bath isincreased during the processing, resulting in a change in composition ofthe structural layer as a function of deposit thickness, as compared toa heat exchanger processed at a uniform chemical composition.

Alternatively, a working fluid with a different temperature than theprocessing bath is passed through the heat exchanger during processing,resulting in a variable temperature across the heat exchanger surface.The structured ceramic material will then have structural propertiesconsistent with local temperature during processing. In eventual use,the heat exchanger may also have an operating temperature gradient owingto the differences in temperature of the heat exchanger, and as such thedesired properties of the ceramic surface layer are aligned with theoperational needs of the heat exchanger.

Example 39. A₉-B₁₁—Coating+Selective Coverage Paint

All steel surfaces used for a bridge are coated in a corrosion resistantcoating to prevent the corrosion of the steel. The surfaces that will beclosest to roadway of the bridge are then painted in a protective paint.This partial paint layer protects the corrosion resistant coating fromthe harsh chloride ions used in deicing agents. Only areas that will beexposed to deicing agents need the protective paint layer, as opposed topainting all structural steel elements of the bridge, thus decreasingoverall painting cost.

Example 40. A₁₀—Gradient Paint

A HX is painted with a corrosion resistant paint via dip or spray. Thepaint is applied such that the paint thickness is thinnest in the middleof the coil and thickest on the outside by the manifolds. The cost ofpainting is reduced while still maintaining the corrosion protection atthe areas most vulnerable to corrosion.

Example 41. A₁₁—Selective Coverage Paint

A brazed aluminum HX coil is painted via dip or spray painting on themanifold and manifold-tube brazing joints. This creates a corrosionprotective coating around the most vulnerable areas of the coil.

Example 42. A₁₂—Selective Coverage Gradient Paint

A HX coil is painted with a corrosion resistant paint via dip or sprayat the manifold and manifold-tube brazing joints only. A gradient iscreated by applying multiple layers or varying spray time in selectedregions of the substrate. The application of the paint is focused on themanifold-tube brazing joints which are most vulnerable to corrosionrelated failure. This process vastly decreases the cost of painting,while maintaining corrosion prevention in areas that are most needed.The absence of the paint in the functional area of the coil (fin pack)also prevents loss in the HX performance.

Example 43

3003 Aluminum panels were tested for improved drying properties asoutlined herein. All panels were tested by measuring the mass of a panelsubject to controlled ambient conditions ranging from 68-70° F., 30-50%relative humidity (RH), and monitoring the mass on the addition of aquantity of two 100 microliter droplets during a subsequent dryingperiod. The bare panel had a drying rate (as measured by mass loss afterdroplet addition) of about 3 mg of water/cm2-hr. Similarly, anelectrocoated panel with polyurethane UV protection was determined tohave a similar drying rate of 3 mg/cm2-hr. Panels coated with variousstructural ceramic layers, as described in PCT/US19/65978, weredetermined to have a drying rate of 20 to 50 mg/cm2-hr. Three differentstructured ceramic layer formulations were applied. One panel includedmagnesium and aluminum oxides/hydroxides (“Structured ceramic1”),applied as described in PCT/US19/65978. Another panel included magnesiumand aluminum oxides/hydroxides (“Structured ceramic2”), deposited undersimilar process conditions for a shorter period of time. A third panelincluded manganese and aluminum oxides/hydroxides (“Structuredceramic3”). Results are shown in FIG. 1 .

Panels similar to those comprising the structural ceramic layer werefurther treated with a functional material layer comprisinghexadecylphosphonic acid to increase the contact angle. The applicationof 100 microliter water droplets resulted in the droplets rolling offthe surface of the panels. No mass measurements are provided, as thedroplets rolled off the surface before the first time point.

Example 44

A series of 3003 aluminum q-panels were coated with a binderlessstructured ceramic surface modification including magnesium and aluminumoxides/hydroxides, similar to that described in Example 33, andsubjected to either an immersion temperature of 70° C. or 80° C., for animmersion time period of 1 minute to 64 minutes. Previous samples madeat these same conditions demonstrated that the porosity and pore sizedistribution of the structured ceramic surface varied as a function ofimmersion time. The capillary climb of de-ionized water of the sampleswas measured and the data demonstrated the ability of process parametersto impact how water interacts with the surface. Longer immersion timesyielded improved capillary climb, and higher temperature immersion alsoyielded improved capillary climb. This showed that varying processparameters across the surface of a material can be used to optimize howthe surface interacts with water for specific applications. Imaging ofthe structured ceramic layers with a scanning electron microscope (SEM)demonstrated differences in both nanometer and micrometer scalefeatures. When capillary climb measurements were taken with a barealuminum q-panel, the air-water interface was unchanged.

Although the foregoing invention has been described in some detail byway of illustration and examples for purposes of clarity ofunderstanding, it will be apparent to those skilled in the art thatcertain changes and modifications may be practiced without departingfrom the spirit and scope of the invention. Therefore, the descriptionshould not be construed as limiting the scope of the invention.

All publications, patents, and patent applications cited herein arehereby incorporated by reference in their entireties for all purposesand to the same extent as if each individual publication, patent, orpatent application were specifically and individually indicated to be soincorporated by reference.

1. A composition comprising a coating or modification on a surface of asubstrate, wherein said coating or modification comprises a gradient inat least one physical or chemical property across at least a portion ofthe substrate surface.
 2. (canceled)
 3. The composition according toclaim 1, wherein said coating or modification comprises a ceramic, apolymeric material or a self-assembled monolayer, and wherein saidcoating or modification comprising the gradient is in a single layer onthe substrate surface.
 4. The composition according to claim 1, whereinsaid coating or modification comprises a plurality of layers, wherein atleast one of said layers comprises the gradient in at least one physicalor chemical property, wherein the at least one layer that comprises thegradient in at least one physical or chemical property comprises aceramic, a polymeric material, or a self-assembled monolayer. 5.(canceled)
 6. The composition according to claim 4, wherein saidplurality of layers comprises a first layer that comprises the gradientin at least one physical or chemical property in contact with thesubstrate and a second functional material layer that does not comprisethe gradient over the first layer.
 7. The composition according to claim4, wherein said plurality of layers comprises a first layer that doesnot comprise the gradient in at least one physical or chemical propertyin contact with the substrate and a second functional material layerthat comprises the gradient over the first layer.
 8. The compositionaccording to claim 1, wherein said coating or modification is applied ina plurality of spatially discrete areas of the surface of the substrate,and wherein one or more area of the substrate surface does not comprisesaid coating or modification.
 9. (canceled)
 10. The compositionaccording to claim 1, wherein said coating or modification is spatiallycontinuous across substantially the entire area of the substratesurface.
 11. The composition according to claim 1, wherein the substrateis modified with a conversion coating or primer on substantially theentire substrate surface, and wherein a layer comprising the gradient inat least one physical or chemical property is coated on top of theconversion coating or primer.
 12. The composition according to claim 11,wherein the layer comprising the gradient in at least one physical orchemical property is applied in a spatially discrete area of theconversion coating or primer, and wherein one or more area of theconversion coating or primer does not comprise the layer comprising thegradient.
 13. The composition according to claim 12, wherein the layercomprising the gradient in at least one physical or chemical property isapplied in a plurality of spatially discrete areas of the conversioncoating or primer.
 14. The composition according to claim 11, whereinthe layer comprising the gradient in at least one physical or chemicalproperty is spatially continuous across substantially the entire area ofthe conversion coating or primer.
 15. The composition according to claim11, wherein the conversion coating or primer comprises a chromate, afluorozirconate, a fluorotitanate, a sol gel, a phosphate, zirconium, arare earth metal, or a blue or black oxide.
 16. The compositionaccording to claim 11, wherein the layer comprising the gradient in atleast one physical or chemical property comprises a ceramic, a polymericmaterial, or a self-assembled monolayer.
 17. The composition accordingto claim 1, wherein a layer comprising the gradient in at least onephysical or chemical property is coated on at least a portion of thesubstrate surface and a substantially uniform functional material layeris coated on top of the layer comprising the gradient and acrosssubstantially the entire area of the substrate surface.
 18. Thecomposition according to claim 17, wherein the layer comprising thegradient in at least one physical or chemical property comprises aceramic, a polymeric material, or a self-assembled monolayer.
 19. Thecomposition according to claim 1, wherein the coating or modification orlayer comprising the gradient in at least one physical or chemicalproperty comprises a ceramic material, and wherein the ceramic materialis a binderless ceramic material that comprises crystallinity greaterthan about 20%.
 20. The composition according to claim 1, wherein theceramic material comprises a metal oxide, a hydrate of a metal oxide, ametal hydroxide, a hydrate of a metal hydroxide, and/or a layered doublehydroxide.
 21. (canceled)
 22. The composition according to claim 19,wherein the ceramic material comprises one or more of: a surface area ofabout 10 m² to 1500 m² per square meter of projected substrate area; asurface area of about 15 m² to 1500 m² per gram of ceramic material; amean pore diameter of about 2 nm to about 20 nm; a thickness of about0.2 micrometers to about 25 micrometers; a porosity greater than about10%; and a void volume of about 100 mm³/g to about 7500 mm³/g asdetermined by mercury intrusion porosimetry.
 23. The compositionaccording to claim 1, wherein the coating or modification or layercomprising the gradient in at least one physical or chemical propertycomprises a latex, an alkane, an alkene, an alcohol, an acrylic, analkyd, an enamel, an epoxy, a siloxane, a fluoropolymer, a urethane, ora molecule with a head group and a tail group, wherein the head groupcomprises a silane group, a sulfonate group, a sulfonic acid group, aboronate group, a boronic acid group, a phosphonate group, a phosphonicacid group, a carboxylate group, a carboxylic acid group, a vinyl group,a hydroxide group, an alcohol group, a thiolate group, a thiol group,and/or an quaternary ammonium group, and wherein the tail groupcomprises a hydrocarbon group, a fluorocarbon group, a vinyl group, aphenyl group, an epoxide group, an acrylic group, an acrylate group, ahydroxyl group, a carboxylic acid group, a thiol group, and/or aquaternary ammonium group.
 24. (canceled)
 25. The composition accordingto claim 1, wherein the at least one physical or chemical property ofthe gradient is selected from thickness, density, pore size, pore sizedistribution, pore filling fraction, chemical or physical composition,oxidation state, metal concentration, crosslinking density, isoelectricpoint, electrical conductivity, thermal conductivity, capacitance, or acombination thereof.
 26. The composition according to claim 1, whereinsaid substrate surface is a surface of a heat exchanger or a componentthereof, a vehicle, an aircraft, a watercraft, or a bridge. 27.(canceled)
 28. The composition according to claim 26, wherein saidsubstrate surface is a surface of a heat exchanger or a componentthereof, wherein the heat exchanger is a brazed aluminum heat exchanger,a copper tube-aluminum fin heat exchanger, or a steel tube-aluminum finheat exchanger.
 29. The composition according to claim 28, wherein theheat exchanger or component thereof comprises greater resistance toenvironmental damage in comparison to an identical heat exchanger orcomponent that does not comprise the composition.
 30. A heat exchangeror a component thereof, comprising a coating or modification on asurface of the heat exchanger or component thereof, wherein said coatingor modification comprises a gradient in at least one physical orchemical property across at least a portion of the heat exchanger orcomponent surface.
 31. The heat exchanger or component thereof accordingto claim 30, wherein the heat exchanger is a brazed aluminum heatexchanger, a copper tube-aluminum fin heat exchanger, or a steeltube-aluminum fin heat exchanger.
 32. The heat exchanger or componentthereof according to claim 30, wherein the heat exchanger or componentthereof comprises greater resistance to environmental damage incomparison to an identical heat exchanger or component that does notcomprise the coating or modification.
 33. A method for protecting asubstrate from environmental damage, comprising applying a compositionaccording to claim 1 to a substrate, wherein the substrate comprisesgreater resistance to environmental damage in comparison to an identicalsubstrate that does not comprise the composition. 34.-36. (canceled)